1. Field of the Invention
This invention relates to the construction of helixes and augers for article handling systems, particularly the helixes of linkless, drum type ammunition storage systems.
The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of Defense.
2. Prior Art
Linkless, drum type ammunition storage systems are well known, and are shown, for example, in U.S. Pat. No. 3,696,704 issued to L. F. Backus et al. on Oct. 12, 1972, and other patents and publications cited therein. Conventionally, such systems comprise a central helix or auger rotating about a central axis within an outer drum having a plurality of centripetally directed, longitudinally extending guides disposed in an annular row. Rounds of ammunition are stored in longitudinally extending columns with their bases respectively between guides, and their tips respectively between turns of the helix. As the helix rotates, it advances the rounds longitudinally.
The conventional helix is substantially a hollow core-tube with a single or double lead helical fin of isosceles triangular cross-section wound around and fixed thereto. This helical fin is made conventionally of a plurality of annular disks each having a radial slit therein. The disks are distorted longitudinally at the slit by a one or two pitch distance and by back-to-back pairs are welded together and to the tube to form a single turn of helical fin of triangular cross-section, and to the immediately preceding and succeeding pairs to form a multi-turn helix.
There are several disadvantages to this conventional construction:
1. Wasted scrap. The annular disks are stamped out of squares of metal. The inner circle and the outer corners are wasted.
2. Weight. Each turn of the helical fin is stressed from one side as the helix is rotated against the rounds of ammunition. The disk on the stressed side is put into tension, while the disk on the lee side is put into compression. The primary failure mode of this structure is buckling of the lee side disk in compression, with failure in tension of the spot-welds or other fasteners between the core-tube and the stressed side disk. Therefore, the disks must be made thick enough to resist such failure.
3. Alignment. Each of the disks must be accurately aligned with and secured to the mating disk, the preceding and succeeding disk and the core tube.
Accordingly, it is an object of this invention to provide a helical fin of triangular cross-section which requires no scrap to produce, is of minimum weight, and which requires no alignment of disks.
A feature of this invention is the provision of a helix having a helical fin of substantially folded plate cross-section made of integrally continuous ribbons of material.
Another feature of this invention is the provision of a process of manufacturing a helix having a helical fin of substantially folded plate cross-section from continuous rectangular ribbons of stock material.